The most common issue with Internet systems is that they are too complex for the ordinary person to understand. Also, a small home-based system may be complex for some people. Consequently, when it comes to bigger agencies and large organizations that deal with lots of computers on the network, the complexity will increase.
Therefore, to learn which ports are open and the rules of engagement, a program called Nmap can be used. It’s a network scanning tool available for IT administrators, network administrators, systems administrators and other IT professionals.